What projects would be tractable that either EA institutions, philanthropic startup projects, or other institutions could do?
To figure out - does COVID cause long term damage to those who recover, how frequently, what kind of damage, how severe, and to whom?
And optionally: which person or institution may be well placed to execute on your idea?
This seems to be very low on neglectedness, and not particularly high on tractability either.
The vast amounts of funding and research from every source that is currently starting / ongoing about COVID.
Examples:
https://www.covid19funding.org/
https://hub.jhu.edu/novel-coronavirus-information/research-preparedness/research-preparedness-covid-19-funding-opportunities/